A conventional two-piece paper fastener is shown in FIGS. 5 and 6 and generally includes a prong base 40 and a compressor 30. The prong base 40 has two prongs 41 extending from two ends thereof and two holes 31 are respectively defined through two ends of the compressor 30 so that the two prongs 41 extend through papers (not shown) and the two holes 31 so position the papers between the prong base 40 and the compressor 30. Two retainers 32 are movably mounted to the compressor 30 so that the two prongs 41 can be folded toward each other and are retained by the two retainers 32. The prong base 40 and the compressor 30 are generally made of metal sheets or plastic sheets, and the metal sheets or the plastic sheets are pressed into pieces of the prong bases 40 and the compressors 30 so that the sides of each the prong base 40 and the compressor 30 have sharp raw material which could cut users' fingers. Besides, the prong base 40 and the compressor 30 with sharp raw material on their sides could result in tragedies if children use them as toys so that the conventional two-piece paper fastener needs to be improved.
The present invention intends to provide a two-piece paper fastener that includes a prong base and a compressor, and each side of the prong base and the compressor has a flange folded inward so as to define a smooth side.